Overheating Issues

I understand that this is an old thread, but I think I have the same problem.

1998 170kt4r sr5. New radiator last year.
When I go to this one upill section at my local trails, I start to get above normal temp. i dont let it reach the red, but the resevior fills up and she runs hot. I go on 100mile drives and stop and go driving in the city, nothing- this only happens off road and uphill. Its really got me stumped, I love getting out on the trail and I want a reliable rig. I tested the fan with a magazine and couldn't get it to stop.

Also, brand new cat and exhaust.
Where should I start??
 
I realize ignition system is electronic, but I wonder if a crankshaft or camshaft position sensor is sending a false reading to the ECM causing a retard in ignition timing which would cause the cylinders to run hot.
 
Has anyone found the cause of this issue yet ? Im having the same exact symptoms. I think its possibly being caused by mud in the radiator since is seems to stiop for a while until i hit some mud and then starts doing it again. Im thinking that because I cant really get the radiator totally clean due to obstructions from the fan and shrouds that when I clean it out Im only getting just enough mud out to keep it from happening but there is probably a ton of mud i cant reach . Im going to either drop the shroud or pull the radiator out completely and really get it clean. Another thing that may be happening is that the first time I cleaned it out with high pressure I may have bent a bunch of the radiator fins and caused poor heat dissipation and airflow. I hope to get to the bottom of it sooner than later and will update here when I drop the radiator. I cant have my 4runner overheating , especially with aluminum heads....
 
Could also be a bad water pump. Fin gone,bearings going out, near end of life and unable to keep up water volume.

Also, coolant channel crud buildup can cause a weak cooling system. Just some thoughts.

Is it worse moving or stopped? Grab the upper return line once the tstat has opened. What does it feel like. Firm, like fighting back or very easy to grab? The system should generate enough psi that the line is firm and gives good resistance to you grabbing it. If not, then pressure caused by weak pump or obstructions in system could be culprits.
 
Wash and wash or air pressure out the exterior of all your rads until water flows. I've had certain silty puddles clog the air flow through my radiator on 2 different occasions
 
So yesterday I moved the shroud and really got in there with the hose. Lots of mud came out. The bottom 6 inches of the radiator were completely clogged up and i really had to work to get water to flow through that area. Id imagine this is from being stuck in deep mud and having it really soak into the fins and cake up. THe rest of the radiator and the AC condensor coil that sits in front of it were very dirty as well. Its not as simple as shooting it with the pressure washer quickly because of all the area that cant be reached. I will test it offroad this weekend to make sure it doesn't overheat again.
 
If you are wheeling in the mud you have got to wash the radiator/condenser and the underside off. I will either do it on the way home or at home.
 
Understand this is an old thread.

What do you think the appropriate steps are to solving this? I am looking for the easiest cheapest thing to check to the most expensive.
 
As has been mentioned the first thing to do is pressure wash the externals of the radiator. I off road a lot and it's pretty surprising just how much dirt gets forced into the fins. None of this garden hose wash, high pressure is what to do.
 
Is accumulated dirt enough to make the engine go to the red zone?

My problem is a bit weird. I was in traffic ~20min without AC in Miami and all of a sudden went into the RED. Turned on the heat to dissipate some of the heat and it then hovered below normal. My running temp is usually right in the middle now it sits a little below middle.
 
CXS said:
As has been mentioned the first thing to do is pressure wash the externals of the radiator. I off road a lot and it's pretty surprising just how much dirt gets forced into the fins. None of this garden hose wash, high pressure is what to do.
Click to expand...

Power washer!!?? Yeah til you bend all fins shut.

Soap and water and a garden hose is all you need. Back flow as much as possible so you're not pushing dirt further into the condenser/rad.
 
Hey I pressure wash them too, but we know what we're doing. Someone searched and pulled an old thread and received immediate advice to high pressure wash their radiator. Not many have a pressure washer so they run to the car wash and blast the radiator from a distance and nothing happens because of the grill and fan/shroud, so they shove it in between and f it all up. Strip the fins right off the row, happens all the time.
 
similar issue

04 w/ 238k. I do a lot of highway miles and some towing. A few yrs ago my engine was overheating a lot and all I could do to reduce the temperature was to raise the RPM to 3k or above, hold it steady, then the temp would drop to normal and I keep driving. Ended up becoming annoying and took it to the dealer for a check up. Replaced radiator, Tstat, flush, and all was good and normal for 1.5 yrs. I randomly tow a trailer, jet skis, etc. and have had no issues - until late. Two wks ago I pulled a 700 mile trip with loaded enclosed trailer and had problems. About six hours in and the temp gauge was up and down. Hit traffic and it went all the way up immediately. All I could to stay alive was to keep moving or drop Neutral, slam the gas up to 4500 RPM and pray the temp drops. All the time braking with the left trying to not hit the vehicles cutting me off. Actually make my destination, I limp to the dealer where they tell me with a straight face that there's air bubbles in my sh*t, flush it and you're good. So I stupidly trust that and head back on the 700 mile round trip. Same issues. Next dealer replaces the water pump and sends me home. I do the 700 miles again and have the same issues all over again. Everything else seems to be in order and has been inspected, the problem only occurs while towing (stress), and the only way to reduce the engine temp is to get the RPM to 3k or above. Suggestions are extremely welcome.
 
kingoftears said:
04 w/ 238k. I do a lot of highway miles and some towing. A few yrs ago my engine was overheating a lot and all I could do to reduce the temperature was to raise the RPM to 3k or above, hold it steady, then the temp would drop to normal and I keep driving. Ended up becoming annoying and took it to the dealer for a check up. Replaced radiator, Tstat, flush, and all was good and normal for 1.5 yrs. I randomly tow a trailer, jet skis, etc. and have had no issues - until late. Two wks ago I pulled a 700 mile trip with loaded enclosed trailer and had problems. About six hours in and the temp gauge was up and down. Hit traffic and it went all the way up immediately. All I could to stay alive was to keep moving or drop Neutral, slam the gas up to 4500 RPM and pray the temp drops. All the time braking with the left trying to not hit the vehicles cutting me off. Actually make my destination, I limp to the dealer where they tell me with a straight face that there's air bubbles in my sh*t, flush it and you're good. So I stupidly trust that and head back on the 700 mile round trip. Same issues. Next dealer replaces the water pump and sends me home. I do the 700 miles again and have the same issues all over again. Everything else seems to be in order and has been inspected, the problem only occurs while towing (stress), and the only way to reduce the engine temp is to get the RPM to 3k or above. Suggestions are extremely welcome.
Click to expand...

Having to maintain a high RPMs makes me think it's the fan clutch going bad and slipping so the fan isn't turning fast enough at lower RPMs,
 
2005 4.7 v8 overheating problems

Good afternoon. I'm new here so sorry for hijacking this post. My 4r is starting to overheat durimg normal commuting. This started a week ago and I checked coolant levels and they are good. The temp will slowly climb past halfway and usually about 10 minutes into each trip it reach red and then slowly drop to 3/4 And back up to red. It will do this for the entire trip. I know there are many possible issues, such as a coolant leak (havent seen any signs), a thermostat that doesn't open, airflow through the radiator, a faulty fan clutch, the cooling fan, a radiator hose issue or even a defective radiator cap. Any recommendations for checking off these possible solutions? Thanks
 
Overheating, Coolant Leak, and Smoking

Sorry guys, don't know if this is the right spot to ask, but I just got my first car, a 04 SR5 4Runner, from my aunt, but the problems that it has sound crazy. The only history I know of it was that the car would overheat and leak coolant after a while. It would not work for my cousins multiple times and the coolant had to be refilled every few weeks. Apparently, from what my family has told me, the coolant would leak towards the oil, or the exhaust, and the car would start smoking, as well as theres a crack somewhere. Theres different things family say, and well, I don't know what it is. I'm new to actually fixing cars, and I only know a bit about cars, so if someone could please help out! Thanks!
 
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